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posted by hubie on Tuesday March 26, @03:40AM   Printer-friendly

https://www.righto.com/2015/11/macbook-charger-teardown-surprising.html

Have you ever wondered what's inside your Macbook's charger? There's a lot more circuitry crammed into the compact power adapter than you'd expect, including a microprocessor. This charger teardown looks at the numerous components in the charger and explains how they work together to power your laptop.

Most consumer electronics, from your cell phone to your television, use a switching power supply to convert AC power from the wall to the low-voltage DC used by electronic circuits. The switching power supply gets its name because it switches power on and off thousands of times a second, which turns out to be a very efficient way to do this conversion.

[...] One unexpected component is a tiny circuit board with a microcontroller, which can be seen above. This 16-bit processor constantly monitors the charger's voltage and current. It enables the output when the charger is connected to a Macbook, disables the output when the charger is disconnected, and shuts the charger off if there is a problem. This processor is a Texas Instruments MSP430 microcontroller, roughly as powerful as the processor inside the original Macintosh.


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  • (Score: 0, Troll) by Anonymous Coward on Tuesday March 26, @03:50AM (3 children)

    by Anonymous Coward on Tuesday March 26, @03:50AM (#1350379)

    Probably connects to the internet also.. Couldn't be more ripe for a virus attack

    • (Score: 4, Informative) by driverless on Tuesday March 26, @09:56AM (2 children)

      by driverless (4770) on Tuesday March 26, @09:56AM (#1350399)

      What's in that article is practically a museum piece compared to what ships today: Much higher integration rather than so many discrete parts, and completely different topology with GaN-based designs.

      Just checked, it's from 2015, it really is a museum piece despite it being less than ten years old because the state of the art has shifted so much in recent years.

      • (Score: 1, Touché) by Anonymous Coward on Tuesday March 26, @02:55PM

        by Anonymous Coward on Tuesday March 26, @02:55PM (#1350420)

        Care to give us a teardown?

      • (Score: 2) by JoeMerchant on Tuesday March 26, @07:10PM

        by JoeMerchant (3937) on Tuesday March 26, @07:10PM (#1350471)

        The USB-C "standard" is quite complex, especially where it comes to power transfer ratings. It's not surprising that early implementations would be a lot of parts, getting more and more integrated over the years.

        Was this museum piece USB-C, or Apple's own flavor? Most of our phones, laptops, even the RPi5, have gone to USB-C in the last few years.

        --
        🌻🌻 [google.com]
  • (Score: 3, Interesting) by DrkShadow on Tuesday March 26, @04:12AM (1 child)

    by DrkShadow (1404) on Tuesday March 26, @04:12AM (#1350380)

    To address the challenges of both phase delay as well as current distortion, a power factor correction stage can be introduced between the diode bridge and the DC/DC converter, as shown in Figure 7. It is possible to reduce this harmonic current content due to the relationship between power factor and harmonic distortion in Equation (2) below.

    https://www.ti.com/seclit/ml/slup390/slup390.pdf?ts=1636232123558 [ti.com]

    Is there any interest in SN stories that consist of papers explaining the deep technical details of ... things?

    • (Score: 5, Interesting) by janrinok on Tuesday March 26, @08:06AM

      by janrinok (52) Subscriber Badge on Tuesday March 26, @08:06AM (#1350392) Journal

      Is there any interest in SN stories that consist of papers explaining the deep technical details of ... things?

      Yes, there is. In many cases the stories themselves do not generate a huge number of comments, and the comments that they receive tend to be 'slow burners. The comments are made over a period of days or even weeks. The article is informative. But they receive a reasonable number of page hits so quite a few people are reading them.

      STEM covers such a wide range of topics that very few are interested in every aspect of it. Some people relish the mathematical stories that we occasionally release, others simply yawn and wait for the next story. The same can be said of hardware, security aspects, business affairs, software etc. Even so, we also try to include 'random' topics which are not closely related to STEM but might be of a general interest to this community.

      Many of us began by building things ourselves going back in some cases to valve (tube) technology, then transistors, the early simply integrated circuits, and so on. The background knowledge to many of the things that are made today is established in the lessons learned in those earlier days which, superficially, have little to connect them to how things are done now. But the lessons that were learned are still important today and knowing what did, and what did not, work in the past remains valuable knowledge.

      However, I will conclude with the usual reminder that we post stories that the community have submitted. If you don't like the stories that we post now then submit those that you would have preferred to have read in their place.

      To answer the title: "But What IS power-factor-correction?!?"

      https://www.electronics-tutorials.ws/accircuits/power-factor-correction.html [electronics-tutorials.ws]

  • (Score: 3, Informative) by bzipitidoo on Tuesday March 26, @04:34AM (1 child)

    by bzipitidoo (4388) on Tuesday March 26, @04:34AM (#1350386) Journal

    The power supplies I saw in EE were real simple: Diodes in a diamond arrangement to flip the negative voltage side of the AC sine wave to positive voltage, then a capacitor to smooth the peaks and valleys and thus provide a reasonable approximation of DC. That was all that a typical automobile with an alternator had. I suppose that's not really a full power supply, just a rectifier. For wall power, throw in a transformer on the AC side to step the voltage down, and that was pretty much it, a very basic power supply. The simplest of all, can't really call this a power supply, is that if it is for DC to DC at a lower voltage, a single resistor can do that. Wasteful, but it works. If you have to keep the voltage within very tight tolerances while under highly variable loads, have to do more. I never did study more sophisticated power supplies.

    • (Score: 2) by RS3 on Wednesday March 27, @05:13AM

      by RS3 (6367) on Wednesday March 27, @05:13AM (#1350539)

      ...a single resistor can do that. Wasteful, but it works. If you have to keep the voltage within very tight tolerances while under highly variable loads, have to do more.

      You may not even have a varying load- your incoming voltage may vary, like "lines" or "mains" AC voltage coming from the power utility.

      Also you might be working with circuits that need very steady stable voltage to work correctly, even though their load is quite consistent. TTL digital electronics are pretty fussy about voltage: 4.75 to 5.24 VDC, ideally tighter to 5V. Digital stuff is also 3.3V, 2.5V, and other lower voltages, but again require pretty tight regulation.

      The simplest power supply would be the resistor you mentioned, with a zener diode [wikipedia.org] to regulate the voltage. Zeners aren't perfect, so we usually use them with some amplifying circuitry, temperature compensation, etc.

  • (Score: 2, Insightful) by pTamok on Tuesday March 26, @10:10AM (6 children)

    by pTamok (3042) on Tuesday March 26, @10:10AM (#1350400)

    I find the high-pitched whine (and lower harmonics) of some switch-mode power supplies intensely irritating, I have a fanless laptop where the transformer for the screen backlight drifts in and out of audibility. And a bathroom light that uses a switch-mode transformer to generate 12V for some lights that were originally halogen, but are now 'replacement-LED'. The load is now below the rated minimum load of the transformer, and it struggles, with irritating noises. [stackexchange.com] It is waiting for me to get a sufficient supply of round tuits [wiktionary.org] to solve the problem.

    • (Score: 3, Touché) by janrinok on Tuesday March 26, @11:06AM

      by janrinok (52) Subscriber Badge on Tuesday March 26, @11:06AM (#1350401) Journal

      It is waiting for me to get a sufficient supply of round tuits [wiktionary.org] to solve the problem.

      A problem that many of us suffer from. I can find plenty of distractions though...

    • (Score: 2, Interesting) by Anonymous Coward on Tuesday March 26, @03:45PM

      by Anonymous Coward on Tuesday March 26, @03:45PM (#1350427)

      I had this problem when electronic ballast fluorescent lights were installed in my shop--industrial ~8 foot long tubes. The lights were irritatingly loud, I even borrowed an audio spectrum analyzer from a friend with a sound reinforcement company to quantify the noise and make sure I wasn't imagining it. The electricians that wired the shop could offer no alternative. I finally got up on a ladder and pulled the ballasts out--thinking I'd replace them with another brand/technology. And then the noise stopped! It seems that they were interacting with the steel fixture that they were inside. I screwed a piece of plywood to the ceiling next to each fixture and moved the ballasts outside the fixture--probably not code, but they've been quiet for the last ~30 years now.

    • (Score: 2) by JoeMerchant on Tuesday March 26, @07:15PM (3 children)

      by JoeMerchant (3937) on Tuesday March 26, @07:15PM (#1350472)

      >And a bathroom light that uses a switch-mode transformer to generate 12V for some lights that were originally halogen, but are now 'replacement-LED'.

      We have a similar set of in-ceiling lights in one bathroom. It's pretty far down my priority list, when the halogens burned out I stuck an LED night light in the outlet beside the sink and so far that's quite a workable solution, though the children do still occasionally switch on the wall switches and start the transformers humming (for no light.)

      What else is on my agenda when I get up into that part of the attic to rework things to a simpler arrangement is a quieter transformer nearby that hums continuously... not sure what it could be, but when the A/C fan is not blowing it's this annoying little hum that I have tracked to one particular ceiling corner of the room... Hopefully it's just a(nother) disused transformer that can be removed, or maybe it's part of the A/C wiring that can be mounted with more isolation instead of screwed hard into a roof truss.

      --
      🌻🌻 [google.com]
      • (Score: 0) by Anonymous Coward on Tuesday March 26, @10:51PM

        by Anonymous Coward on Tuesday March 26, @10:51PM (#1350500)

        Doorbell?

      • (Score: 2) by RS3 on Wednesday March 27, @05:17AM (1 child)

        by RS3 (6367) on Wednesday March 27, @05:17AM (#1350540)

        Yeah, if 12VAC, likely doorbell, or 24VAC for HVAC thermostat / controller power?

        • (Score: 2) by JoeMerchant on Wednesday March 27, @09:52PM

          by JoeMerchant (3937) on Wednesday March 27, @09:52PM (#1350558)

          Far from the doors, no evidence of any prior doorbell installations but... it was built in 1962 so who knows what all got installed and removed in the 50 years before we bought it.

          If it is a doorbell, they located the transformer almost as far as possible from the doors on an exterior wall...

          --
          🌻🌻 [google.com]
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